Composition containing polymer having ionic functional group, ink composition, and image-forming method and image-forming apparatus employing the ink composition

ABSTRACT

The present invention provides an ink composition containing a pigment dispersed uniformly in a solvent and a block polymer having an ionic functional group, an image-forming method and an image-forming apparatus employing the ink composition.  
     The composition comprises a pigment, a solvent and a polymer having an ionic functional group, an acid residue, or a base residue at the terminal. The polymer having an ionic functional group, an acid residue, or a base residue at the terminal is a block polymer of ABX type having A, B, and X segments, wherein A and B are respectively a block segment having a vinyl ether structure as the repeating unit, and X is a terminal segment having an ionic functional group, an acid residue, or an base residue.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a composition containing aparticulate substance, a solvent, and a polymer having an ionicfunctional group. The present invention relates also to an inkcomposition comprising the above polymer-containing composition, and animage-forming method and an image-forming apparatus employing the inkcomposition. In particular, the present invention relates to apigment-dispersion ink composition which comprises water as the solventand a pigment as the particulate substance; an image-forming compositionuseful for printers, displays, and the like; and image-forming methodand an image forming apparatus employing the pigment-dispersion inkcomposition.

[0003] 2. Related Background Art

[0004] Various aqueous liquid dispersions are known which contain aparticulate solid matter as functional materials, including pesticidessuch as herbicides, and insecticides; medicines such as anticanceragents, anti-allergy agents, and anti-inflammatory agents; andparticulate substances such as coloring materials like inks and tonerscontaining a colorant. In recent years, digital printing techniques areprogressing remarkably rapidly. Typical examples of the digital printingtechniques are electrophotographic techniques and ink-jet techniques.Such digital printing techniques are becoming more and more important inoffices and homes.

[0005] Among the digital printing techniques, the ink-jet recordingtechniques have remarkable advantages of compactness and less powerconsumption of the apparatus as a direct recording method, contributingimprovement of image quality by using finer nozzles. In an example ofthe ink-jet technique, an ink fed from an ink tank is vaporized into abubble by heating in a nozzle to be ejected from the nozzle to form animage on a recording medium. In another example, a piezo element isenergized to eject an ink through a nozzle.

[0006] In these methods, since the ink employed is usually an aqueousdye solution, the ink can run on superposition of colors, or the ink canfeather in the fiber direction of the paper in the recorded area of therecording medium. For prevention thereof, use of a pigment-dispersionink is investigated (U.S. Pat. No. 5,085,698). However, many problemsare still remaining unsolved.

[0007] The present invention has been made to solve the above problemsin the prior art techniques. The present invention intends to provide acomposition containing a particulate substance dispersed in a solventand a block polymer having an ionic functional group.

[0008] The present invention intends also to provide an ink compositioncontaining a pigment as the particulate substance, water as the solvent,in which the pigment is dispersed with high dispersibility.

[0009] The present invention intends further to provide apigment-dispersion ink composition for ink-jet recording, which containsa particulate pigment material dispersed with high dispersion stabilityin the solvent, and which forms an image with high fixability and highsmearing resistance.

[0010] The present invention intends still further to provide animage-forming method employing the above pigment-dispersion inkcomposition for ink-jet recording, and an image-forming apparatus forthe image-forming method.

SUMMARY OF THE INVENTION

[0011] A first embodiment of the present invention is a compositioncontaining a polymer having an ionic functional group, which contains aparticulate substance, a solvent, and a polymer which has an ionicfunctional group, an acid residue, or a base residue at the terminal.

[0012] The composition of the present invention contains preferably aparticulate substance, a solvent, and a block polymer which has an ionicfunctional group, an acid residue, or a base residue at the terminal.

[0013] The polymer having an ionic functional group, an acid residue, ora base residue at the terminal is preferably a block polymer containingsegments of A, B, and X, where A and B are respectively a block segmenthaving a vinyl ether structure as the repeating unit, and X is aterminal segment having an ionic functional group, an acid residue, oran base residue.

[0014] The block segment A is preferably constituted of the repeatingunit represented by General Formula (1):

[0015] (in the formula, R₁ is selected from the group consisting oflinear and branched alkyl groups of 1-18 carbons, -Ph, -Pyr, -Ph-Ph,-Ph-Pyr, —(CH(R₅)—CH(R₆)—O)_(p)—R₇, and —(CH₂)_(m)—(O)_(n)—R₇; thehydrogen atom in the aromatic ring may be substituted by a linear orbranched alkyl group of 1-4 carbons; and the carbon atom in the aromaticring may be substituted respectively by a nitrogen atom;

[0016] p is an integer of 1 to 18, m is an integer of 1 to 36, n is 0 or1;

[0017] R₅ and R₆ are independently —H or —CH₃;

[0018] R₇ is selected from the group consisting of Hydrogen, linear andbranched alkyl groups comprising 1 to 18 carbons, -Ph, -Pyr, -Ph-Ph,-Ph-Pyr, —CHO, —CH₂CHO, —CO—CH═CH₂, —CO—C(CH₃)═CH₂, —CH₂COOR₈, and whenR₇ is other than a hydrogen atom, the hydrogen atom bonding to a carbonatom in R₇ may be substituted by a substituent selected from the groupconsisting of a linear or branched alkyl group of 1-4 carbons, —F, —Cland —Br, and the carbon atom in the aromatic ring may be substitutedrespectively by a nitrogen atom;

[0019] R₈ is H or an alkyl of 1-5 carbons;

[0020] Ph represents phenyl, and Pyr represents pyridyl).

[0021] The block segment B is preferably constituted of the repeatingunit represented by General Formula (2):

[0022] (in the formula, R2 is selected from the group consisting of Pyr,—(CH(R₅)—CH(R₆)—O)_(p)—R₇ and —(CH₂)_(m)—(O)_(n)—R₇; p, m, n, R₅, R₆ andR₇ are the same as those defined above).

[0023] The ionic functional group, acid residue, or base residue of theterminal segment X is preferably selected from carboxylic acid, sulfonicacid, phosphoric acid, and metal salts thereof, amines, acid salts ofamines.

[0024] The terminal segment X is preferably the segment represented byGeneral Formula (3):

[0025] General Formula (3)

[0026] (in the formula, L is a coupling group for coupling with theterminal of a block polymer selected from the group consisting of asingle bond, —O—, —COO—, —OCO—, —CONH— and —NHCO—; M is a substituted orunsubstituted linear or branched alkylene group of 1-30 carbons; R₉ andR₁₀ are independently selected from the group consisting of a hydrogenatom, an alkyl group, COOR₁₁ and NR₁₁R₁₂; R₁₁ and R₁₂ representindependently a substituent selected from the group consisting of ahydrogen atom, an alkyl group, and a counter ion group of the carboxyanion; Z represents a substituent selected from the group consisting of—COOH, a carboxylic ester group, —COO⁻, —SO₃H, a sulfonic ester group,—SO₃ ⁻, —OPO₃H₂, phosphoric ester group, —OPO₃H⁻, —OPO₃ ²⁻, an aminogroup and an acid salt of an amino group).

[0027] The aforementioned particulate substance is preferably a pigment.

[0028] The aforementioned solvent is preferably water.

[0029] The aforementioned block polymer is preferably responsive tostimulation to change the properties thereof.

[0030] The stimulation is preferably any of temperature change, exposureto electromagnetic wave, pH change, and concentration change.

[0031] A second embodiment of the present invention is an inkcomposition comprising the above composition.

[0032] The ink composition is preferably an ink-jet ink composition.

[0033] A third embodiment of the present invention is an image-formingmethod employing the above ink composition.

[0034] In the image-forming method for recording an image by ejecting anink from an ink ejection unit onto a recording medium, the ink ispreferably the aforementioned ink composition.

[0035] The image is formed from the ink composition and fixed on arecording medium preferably by contact of the ink composition with astimulating substance which gives stimulation to the ink composition.

[0036] The stimulating substance which gives the aforementionedstimulation is preferably provided preliminarily on the recordingmedium.

[0037] The ejection of the ink from the ink ejection unit is preferablyconducted by action of thermal energy to the ink.

[0038] A fourth embodiment of the present invention is an image-formingapparatus employing the above image-forming method.

[0039] A fifth embodiment of the present invention is a recording mediumfor the aforementioned image-forming method in which the ink compositionis ejected from the ink-ejection unit onto the recording medium, whereina stimulating substance for stimulating the ink composition ispreliminarily provided on the recording medium.

[0040] A sixth embodiment of the present invention is a block polymercontaining segments of A, B, and Y, where A and B are block segments asdefined above having a vinyl ether structure as the repeating unit, andY is a terminal segment represented by General Formula (4):

[0041] General Formula (4)

—L′—M′—Z′  (4)

[0042] (in the formula, L′ is a coupling group for coupling with theterminal of a block polymer selected from the group consisting of asingle bond, —O—, —COO—, —OCO—, —CONH— and —NHCO—; M′ is a substitutedor unsubstituted linear or branched alkylene group of 2-30 carbons; andZ′ represents a substituent selected from the group consisting of —COOH,a carboxylic ester group, —COO⁻, —SO₃H, a sulfonic ester group, —SO₃ ⁻,—OPO₃H₂, a phosphoric ester group, —OPO₃H⁻, —OPO₃ ²⁻, an amino group,and an acid salt of an amino group).

[0043] The feature of the present invention is further described below.

[0044] In the present invention, the particulate substance is a pigment.The solvent is preferably water, although any of water, aqueoussolvents, and organic solvents may be used as the solvent. The use ofwater as the solvent is one feature of the present invention.

[0045] With the composition of the present invention responsive tostimulation, sufficient fixation can be achieved by stimulating thecomposition in the process of image formation to cause increase of inkviscosity or a like change. The stimulation is selected from temperaturechange, exposure to electromagnetic wave, pH change, and temperaturechange suitably for the image formation: two or more kinds ofstimulation may be combinedly employed.

[0046] The composition of the present invention is useful as the ink forink-jet recording.

[0047] The present invention covers an image-forming method employingthe aforementioned composition, including an image-forming method forrecording by ejecting an ink from an ink ejection unit onto a recordingmedium.

[0048] For using the aforementioned stimulation-responsive composition,the image-forming method of the present invention employs a means forgiving stimulation. For example, the image is fixed on a recordingmedium by contact of the stimulation-responsive ink composition with astimulating substance.

[0049] The stimulating substance may be an ink composition differentfrom the ink composition of the present invention.

[0050] The stimulating substance may be provided preliminarily on therecording medium.

[0051] The image-forming methods of recording an image by ejecting anink composition from an ink-ejecting unit onto a recording mediuminclude ejection of an ink by action of a thermal energy to an inkcomposition, and ejection of an ink by use of a piezo element.

[0052] A further embodiment of the present invention is an image-formingapparatus employing the aforementioned image-forming method.

[0053] A further embodiment of the present invention is a recordingmedium onto which a stimulating substance capable of stimulating thestimulation-responsive composition is provided preliminarily.

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] FIGURE shows schematically the system of an image-formingapparatus of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] The inventors of the present invention completed the presentinvention as the results of comprehensive investigation on the prior arttechniques and the disadvantages thereof.

[0056] The composition containing a polymer having an ionic functionalgroup (hereinafter simply referred to as a “polymer-containingcomposition”) of the present invention comprises a particulatesubstance, a solvent, and a polymer having an ionic functional group, anacid residue, or a base residue at the terminal.

[0057] The polymer having an acid residue or a base residue at theterminal contained in the polymer-containing composition of the presentinvention is preferably a block polymer.

[0058] In particular, the block polymer in the present invention havingan ionic functional group, an acid residue, or a base residue at theterminal is preferably a block polymer containing segments of A, B, andX, where A and B are block segments having a vinyl ether structure asthe repeating unit, and X is a terminal segment having an ionicfunctional group, an acid residue, or a base residue.

[0059] The polymer-containing composition of the present inventioncontains the particulate substance having the intended function andbeing dispersed uniformly owing to the presence of the aforementionedblock polymer. Further the polymer-containing composition of the presentinvention is a functional material responsive to stimulation.

[0060] Typical examples of the composition of the present inventioninclude compositions for pesticides such as herbicides and insecticides;compositions for medicines such as anticancer agents, anti-allergyagents, and anti-inflammatory agents; compositions for cosmetics such aslipsticks, foundation make-ups, cheek colorants and moisture-retainingcreams; and compositions used as colorants of color inks and toners.

[0061] The particulate substance in the present invention means acompound or material having a desired function contained in thepolymer-containing composition of the present invention. For example,the particulate substance includes active compounds having a herbicidalactivity or active compounds having an insecticidal activity of thepesticides; compounds of medical compositions for mitigating anobjective symptom; and effective components of cosmetics such as acompound exhibiting moisture-retaining effects of moisture-retainingcreams; and particulate solid substance such as pigments and dyes ofcolorants.

[0062] The preferred particulate substance in the present invention maybe a pigment, a metal, a herbicide, an insecticides, a biologicalmaterial, and a medicine to be suitable for the use of thepolymer-containing composition of the present invention.

[0063] The particulate substance is contained in the polymer-containingcomposition in the range of 0.1 to 50 mass %, preferably 1 to 30 mass %based on the total weight of the composition.

[0064] The solvent contained in the polymer-containing composition ofthe present invention is a medium capable of dissolving, suspending, ordispersing the components contained in the composition, without speciallimitation. The solvent in the present invention includes organicsolvents such as linear, branched, and cyclic aliphatic hydrocarbons,aromatic hydrocarbons, and heterocyclic hydrocarbons; aqueous solvents;and water. Water and aqueous solvents are used suitably in the presentinvention.

[0065] The aqueous solvent includes polyhydric alcohols such as ethyleneglycol, diethylene glycol, triethylene glycol, polyethylene glycol,propylene glycol, polypropylene glycol, and glycerin; polyhydric alcoholethers such as ethylene glycol monomethyl ether, ethylene glycolmonoethy ether, ethylene glycol monobutyl ether, diethylene glycolmonoethyl ether, and diethylene glycol monobutyl ether; andnitrogen-containing solvents such as N-methyl-2-pyrrolidone, substitutedpyrrolidones, and triethanolamine. In use for an ink, monohydricalcohols such as methanol, ethanol, and isopropyl alcohol may beemployed to facilitate drying on the paper sheet.

[0066] The block polymer contained in the polymer-containing compositionof the present invention has an ionic functional group, acid residue, orbase residue at the terminal. Specifically, the block polymer containssegments of A, B, and X. The segments A and B have a repeating unit of avinyl ether structure, and the segment X is a terminal segment having anionic functional group, acid residue, or base residue.

[0067] The block polymer in the present invention is composed of thesegments A, B, and X. The terminal segment X should be situated at theterminal, but combination of the segments A and B is not limited. Forexample, the combination may be ABX, BAX, ABAX, BABX, AABX, ABBX, or thelike. Such a block polymer of the present invention is hereinafterreferred to as an ABX type block polymer.

[0068] The block segment of the block polymer in the present inventionmay be a copolymer or a graduation polymer.

[0069] The ABX type block copolymer used in the present invention can besynthesized specifically by a living polymerization process, a grouptransfer polymerization process, or a macro-chain transfer process. Theliving polymerization includes anion polymerization, cationpolymerization, and radical polymerization. In the synthesis of theblock polymer, the ABX block polymer can be synthesized by firstlypolymerizing a monomer for the A segment, additionally polymerizinganother monomer for the B segment to form an AB block polymer, andfinally introducing the X component capable of bonding to thepolymerization terminal to form the ABX block polymer. The block polymercan be synthesized similarly by group transfer polymerization, ormacro-chain transfer polymerization. In the present invention,preferably a cation living polymerization process is employed. Aoshima'sprocess is well known for the cation living polymerization (e.g.,Journal of Polymer Science, Part A, Polymer Chemistry, vol.39, p.746,2001). The useful monomer includes vinyl ether type monomers, andstyrene type monomers. The useful initiator includes protonic acids suchas hydrochloric acid, sulfuric acid, methanesulfonic acid,trifluoroacetic acid, trifluoromethanesulfonic acid, and perchloricacid; combination of a Lewis acid such as BF₃, AlCl₃, TiCl₄, SnCl₄,FeCl₃, RAlCl₂, and R_(1.5)AlCl_(1.5) with a cation source (the cationsource including protonic acids, water, alcohols, and adducts of a vinylether and a carboxylic acid). The initiator is used for thepolymerization of monomers in the presence preferably of a Lewis basesuch as ethyl acetate and tetrahydrofuran capable of stabilizing thecarbocation.

[0070] The block polymer constituting the polymer-containing compositionof the present invention keeps most of the properties of the blocksegments or the repeating unit structure of the respective blocksegments to exhibit the properties of the both kinds of segments. Inparticular, the block segments or the unit moieties responsive tostimulation will function effectively and efficiently in comparison withrandom copolymers.

[0071] The ABX type block polymer used in the present invention haspreferably a hydrophilic segment and a hydrophobic segment. At least oneof the block segments, the hydrophilic block, can respond to thestimulation (for example, changes hydrophilicity to hydrophobicity) tochange the property of the composition, or the hydrophobic block segmentin a certain conditions can respond to the stimulation to becomehydrophilic to change the properties of the composition.

[0072] A preferred example of the stimulation-responsiveness of theblock copolymers is the ABX type block polymer contained in thepolymer-containing composition of the present invention in which atleast one kind of the block segments is responsive to the stimulation.In such a composition, under certain conditions, the polymer isdispersed in a micelle state in the solvent with thestimulation-responsive block segments kept hydrophobic to exhibit a lowviscosity: on receiving stimulation, the stimulation-responsive blocksegment of the polymer becomes hydrophilic, and the polymer changes itsstate from the low viscosity dispersion state to a highly viscouspolymer solution state. In such a manner, the polymer-containingcomposition changes its state in response to stimulation.

[0073] In the present invention, as described above, excellentstimulation-responsiveness can be obtained by using water as thesolvent. Whereas the above explanation is made by taking the ABX typeblock polymers only, the block polymer is not limited to the ABX type,but may be of an ABDX type, or an ADBX type, or of a random structure ofthe A and B block segments containing other repeating units, providedthat the property of the polymer-containing composition of the presentinvention changes on receiving the stimulation. The constituting blocksegment may have a structure of a graft polymer or a graduation polymer.In the above description, the symbol D denotes a block segment otherthan the segments A and B.

[0074] In the structure of the ABX type block polymer in the presentinvention, the vinyl ether structure of the repeating unit of the Ablock segment has preferably the structure represented by the aboveGeneral Formula (1), but is not limited thereto. The structure may becombination of two or more kinds of the vinyl ether structures.

[0075] In the structure of the ABX type block polymer in the presentinvention, the vinyl ether structure of the repeating unit of the Bblock segment has preferably the structure represented by the aboveGeneral Formula (2). The structure may be combination of two or morekinds of the vinyl ether structures.

[0076] The terminal segment X of the ABX type block polymer of thepresent invention is preferably the segment represented by the aboveGeneral Formula (3).

[0077] In this Patent Specification, -Ph denotes a phenyl group; -Pyr, apyridyl group; -Ph-Ph, a biphenylyl group; and -Ph-Pyr, a pyridylphenyl.The groups of pyridyl, biphenylyl and pyridyldiphenyl may be any of thepossible positional isomers.

[0078] The present invention provides also a polymer compound of a novelblock polymer.

[0079] The polymer compound of the present invention is a block polymercontaining segments of A, B, and Y, where A and B are block segments asdefined above having a vinyl ether structure as the repeating unit, andY is a terminal segment represented by the above General Formula (4).

[0080] The block polymer in this invention is composed of the segmentsA, B, and Y. The terminal segment Y should be situated at the terminal,but combination of the segments A and B is not limited. Such a blockpolymer of this invention is hereinafter referred to as an ABY typeblock polymer.

[0081] Examples of the repeating units contained in the block segments Aand B of the block polymer of the present invention are shown belowwithout limiting the structure employed in the present invention.

[0082] In the formulas, Me denotes methyl; Et, ethyl; and i-Pr,isopropyl.

[0083] Examples are shown below of the structures of the block polymershaving the vinyl ether structure without limiting the polymer of thepresent invention.

[0084] Still further examples of the terminal structure of the terminalsegment X of the block polymer of the present invention are shown belowwithout limiting the terminal segment X thereto.

[0085] —OCO—CH₂CH₂CH₂COOH

[0086] —CH—(COOH)₂

[0087] —O—CH₂CH(CH₃)COOCH₃

[0088] —O—CH₂CH(CH₃)CH₂N(CH₃)₂

[0089] —O—CH₂CH₂CH₂N(CH₃)₂H⁺Cl⁻

[0090] —O—CH₂CH₂CH₂SO₃H

[0091] —O—CH₂CH₂CH₂SO₃ ⁻K⁺

[0092] —O—CH₂CH₂CH₂CH₂SO₂CH₃

[0093] —O—CH₂CH₂CH₂CH₂OPO₃H₂

[0094] —O—CH₂CH₂CH₂CH₂OPO₃(C₂H₅)₂

[0095] —O—CH₂CH₂CH₂CH₂OPO₃H⁻

[0096] —O—CH₂CH₂CH₂CH₂OPO₃ ²⁻

[0097] In the above polyvinyl ethers, the numbers u, v, and w of therepeating units are independently in the range preferably from 1 to10,000, and more preferably the total (u+v+w) is in the range from 10 to20,000.

[0098] The number-average molecular weights of the block polymer and thehigh molecular compound of the present invention range from 500 to2,000,000, preferably from 1,000 to 500,000. The polymer of themolecular weight of less than 500 tends to result in insufficientdispersing power, whereas the polymer of the molecular weight of higherthan 2,000,000 tends to give an excessively high viscosity.

[0099] The content of the block polymer in the polymer-containingcomposition of the present invention ranges preferably from 0.1 to 50mass %. At the content of less than 0.1 mass % of the block polymer, thedispersibility of the particulate substance in the composition of thepresent invention tend to be insufficient, whereas at the content ofmore than 50 mass %, the viscosity tends to be excessively high. Morepreferably the content is in the range from 0.5 to 30 mass %.

[0100] The polymer-containing composition of the present inventionchanges its state (properties) in response to stimulation. For example,the change of the state includes a phase change between a sol state anda gel state, a phase change between a solution state and a solid state,and change of chemical structure. The stimulation in the presentinvention includes a temperature change; electric field application;exposure to light (electromagnetic wave) such as ultraviolet ray,visible light, and infrared light; change of pH of the composition;addition of a chemical substance; and concentration change of thecomposition.

[0101] The stimulation-responsiveness in the present invention means thecapability of changing a property of the composition in response to theabove stimulation. In other words, the stimulation-responsiveness meansthe quality of changing significantly the shape or property of thecomposition on application of stimulation such as exposure toelectromagnetic wave, application of an electric field, change oftemperature, addition of a chemical substance, and change of theconcentration of the composition. The stimulation in the presentinvention may be combination of two of more kinds of stimulation, andthe property to be changed is selected to meet the purpose of use of thecomposition.

[0102] For medical uses, the change may be release of a functionalsubstance by changing the chemical structure on application of thestimulation. For cosmetic uses, the change may be a change of the phasestate of the composition on application of the stimulation to preventvolatilization of a desired functional substance. For colorant uses, thechange may be a phase change (for example, change from sol to gel) oncontact with a recording medium by stimulation to prevent ink-running orfeathering or to improve the fixability onto the recording medium.

[0103] The polymer-containing composition of the present invention isuseful, as described above, in various application fields such aspesticides, medicines, cosmetics, and coloring materials, beingparticularly useful as an ink material containing a pigment or a dye andwater or a solvent for dissolution. The ink material can be improved invarious properties including fixability by use of the polymer-containingcomposition of the present invention as an ink composition.

[0104] In the ink composition which is a preferred embodiment of thepolymer-containing composition of the present invention, the particulatesubstance is usually a pigment. Specific examples of the pigment usefulfor the ink composition employing the polymer-containing composition ofthe present invention are shown below.

[0105] The pigment may be either an organic pigment or an inorganicpigment. A black pigment and three primary-color pigments of cyan,magenta, and yellow are used as the ink pigments. Another color pigment,a colorless or a pale color pigment other than the aforementionedpigments, or a metallic luster pigment, or the like may be used. Eithera commercial pigment or a newly synthesized pigment may be used. A dyemay be used in combination with the above pigment.

[0106] Examples of commercial pigments of black, cyan, magenta, andyellow are shown below.

[0107] The black pigment includes Raven 1060, Raven 1080, Raven 1170,Raven 1200, Raven 1250, Raven 1255, Raven 1500, Raven 2000, Raven 3500,Raven 5250, Raven 5750, Raven 7000, Raven 5000, ULTRA II, Raven 1190,and ULTRA II (the above pigments produced by Columbian Carbon Co.);Black Pearls L, MOGUL-L, Regal 400R, Regal 660R, Regal 330R, Monarch800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1300, and Monarch1400 (the above pigments produced by Cabot Co.); Color Black FW1, ColorBlack FW2, Color Black FW200, Color Black 18, Color Black S160, ColorBlack S170, Special Black 4, Special Black 4A, Special Black 6, Printex35, Printex U, Printex 140U, Printex V, and Printex 140V (the abovepigments produced by Degussa Co.); No.25, No.33, No.40, No.47, No.52,No.900, No.2300, MCF-88, MA 600, MA 7, MA 8, and Ma 100 (the abovepigments produced by Mitsubishi Chemical Co.); but is not limitedthereto.

[0108] The cyan pigment includes C.I.Pigment Blue-1, C.I.Pigment Blue-2,C.I.Pigment Blue-3. C.I.Pigment Blue-15, C.I.Pigment Blue-15:2,C.I.Pigment Blue-15:3, C.I.Pigment Blue 15:4, C.I.Pigment Blue-16,C.I.Pigment Blue-22, and C.I.Pigment Blue-60; but is not limitedthereto.

[0109] The magenta pigment includes C.I.Pigment Red-5, C.I.PigmentRed-7, C.I.Pigment Red-12, C.I.Pigment Red-48, C.I.Pigment Red-48:1,C.I.Pigment Red-57, C.I.Pigment Red-112, C.I.Pigment Red-122,C.I.Pigment Red-123, C.I.Pigment Red-146, C.I.Pigment Red-168,C.I.Pigment Red-184, C.I.Pigment Red-202, and C.I.Pigment Red-207; butis not limited thereto.

[0110] The yellow pigment includes C.I.Pigment Yellow-12, C.I.PigmentYellow-13, C.I.Pigment Yellow-14, C.I.Pigment Yellow-16, C.I.PigmentYellow-17, C.I.Pigment Yellow-74, C.I.Pigment Yellow-83, C.I.PigmentYellow-93, C.I.Pigment Yellow-95, C.I.Pigment Yellow-97, C.I.PigmentYellow-98, C.I.Pigment Yellow-114, C.I.Pigment Yellow-128, C.I.PigmentYellow-129, C.I.Pigment Yellow-151, and C.I.Pigment Yellow-154; but isnot limited thereto.

[0111] A self-water-dispersible pigment is also useful for the inkcomposition of the present invention. The water-dispersible pigmentincludes the ones having a polymer adsorbed thereon utilizing a sterichindrance effect, and the ones utilizing electrostatic repulsion.Examples of commercial products are CAB-O-JET 200, and CAB-O-JET 300(produced by Cabot Co.); Microjet Black CW-1 (produced by OrientChemical Co.); and so forth.

[0112] The pigment for the ink composition of the present invention isused in an amount preferably of 0.1 to 50 mass % based on the weight ofthe ink composition. At a pigment content of lower than 0.1 mass %,sufficient image density cannot be obtained, whereas at a pigmentcontent of higher than 50 mass %, the pigment can aggregate to becomenon-dispersible. More preferably the pigment content is in the range of0.5 to 30 mass %.

[0113] The useful solvent includes water, aqueous solvents, and organicsolvents. Of these solvents, water is preferred. The water is preferablydeionized water free from metal ions, pure water, or ultra-pure water.

[0114] The water is contained in the ink composition at a contentpreferably of 5 to 99 mass %, more preferably 10 to 90 mass %. At thewater content of lower than 5 mass %, the colorant dispersion can beinsufficient, whereas at the water content higher than 99 mass %, thefunction or performance of the other component tends to be insufficient.

[0115] The aqueous solvent includes polyhydric alcohols such as ethyleneglycol, diethylene glycol, triethylene glycol, polyethylene glycol,propylene glycol, polypropylene glycol, and glycerin; polyhydric alcoholethers such as ethylene glycol monomethyl ether, ethylene glycolmonoethy ether, ethylene glycol monobutyl ether, diethylene glycolmonoethyl ether, and diethylene glycol monobutyl ether; andnitrogen-containing solvents such as N-methyl-2-pyrrolidone, substitutedpyrrolidone, and triethanolamine. In use for an ink, monohydric alcoholssuch as methanol, ethanol, and isopropyl alcohol may be employed tofacilitate drying on the paper sheet (a recording medium).

[0116] The aqueous solvent is contained in the ink composition at aconcentration in the range of preferably 0.1 to 50 mass %, morepreferably 0.5 to 40 mass %. At the content of lower than 0.1 mass %,the function of the aqueous solvent tends to be insufficientlyexhibited, whereas, at the content of higher than 50 mass %, theviscosity tends to be excessively high.

[0117] The content of the block polymer in the polymer-containingcomposition of the present invention is in the range of preferably 0.1to 50 mass %, more preferably 0.5 to 30 mass %. At the content lowerthan 0.1 mass % of the block polymer, the dispersibility of theparticulate substance in the composition of the present invention tendto be insufficient, whereas at the content higher than 50 mass %, theviscosity tends to be excessively high.

[0118] The above ink composition can be responsive to stimulation. Owingto the responsiveness, the ink viscosity or other property can bechanged by stimulation in an image-forming process to improve thefixability. The stimulation is selected from change of temperature,exposure to magnetic wave, change of pH, change of concentration, and soforth suitably for image formation.

[0119] The present invention is particularly suitable for the inkcomposition which changes the property in response to the stimulation.The pigment ink of the present invention, in which the pigment is highlydispersible, is improved to cause less ink-running and less feathering,and is excellent in fixability and smearing resistance. Thereby the inkcomposition as the pigment dispersion ink material of the presentinvention is useful as an image-forming material for high image quality,and high-speed image formation with low energy consumption.

[0120] The polymer-containing composition of the present inventionchanges its state (property) in response to stimulation. In the presentinvention, the “stimulation” includes change of temperature; applicationof electric field; exposure to light (electromagnetic wave) likeultraviolet ray, visible light, or infrared light; change of pH of thecomposition; addition of a chemical substance; and concentration changeof the composition.

[0121] The preferred stimulation in the present invention isspecifically shown below.

[0122] A first kind of the stimulation is change of the temperaturearound the phase transition temperature of the composition. A secondkind of the stimulation is exposure to magnetic wave, preferably in thewavelength range of the electromagnetic wave from 100 to 800 nm. A thirdkind of the stimulation is pH change of the composition, preferably inthe range from pH 3 to pH 12. A fourth kind of the stimulation is changeof the concentration, including change of the concentration of thepolymer dissolved in the composition by evaporation or absorption of thesolvent from the composition. The concentration change is preferablycaused around the phase transition concentration of the composition. Twoof more kinds of the above stimulation may be applied in combination.

[0123] An additive, an auxiliary agent, or the like may be incorporated,as necessary, into the ink composition of the present invention. Anexample of the additive for the ink composition is a dispersionstabilizer for dispersing the pigment in the solvent. Although the blockpolymer in the ink composition of the present invention has capabilityof dispersing a particulate solid matter like the pigment, an additionaldispersion stabilizer may be added to improve further the dispersionstate. The additional dispersion stabilizer may be a resin having both ahydrophilic portion and a hydrophobic portion, or a surfactant.

[0124] The resin having a hydrophilic portion and a hydrophobic portionincludes copolymers of a hydrophilic monomer and a hydrophobic monomer.The hydrophilic monomer includes acrylic acid, methacrylic acid, maleicacid, fumaric acid, monoesters of the aforementioned carboxylic acids,vinyl sulfonic acid, styrenesulfonic acid, vinyl alcohol, acrylamide,and methacryloxyethyl phosphate. The hydrophobic monomer includesstyrene, styrene derivatives such as α-methylstyrene, vinylcyclohexane,vinylnaphthalene derivatives, acrylic esters, and methacrylic esters.The copolymer may be of various structures including random copolymers,block copolymers, and graft copolymers. Naturally, the hydrophilicmonomers and the hydrophobic monomers are not limited to the onesmentioned above.

[0125] The surfactant includes anionic surfactants, nonionicsurfactants, cationic surfactants, and amphoteric surfactants.

[0126] The anionic surfactant includes fatty acid salts, alkylsulfatesalts, alkylarylsulfonate salts, alkyldiaryl ether disulfonate salts,dialkyl sulfosuccinate salts, alkylphosphate salts, naphthalenesulfonicacid-formaldehyde condensates, polyoxyethylenealkyl phosphate salts,glycerol borate, and fatty acid esters.

[0127] The nonionic surfactant includes polyoxyethylene alkyl ether,polyoxyethylene-oxypropylene block copolymer, sorbitan fatty acid ester,glycerin fatty acid ester, polyoxyethylene fatty acid ester,polyoxyethylenealkylamine, fluorine type surfactants, and silicone typesurfactants.

[0128] The cationic surfactant includes alkylamine salts, quaternaryammonium salts, alkylpyridinium salts, and alkylimidazolium salts.

[0129] The amphoteric surfactant includes alkylbetaine, alkylamineoxide, and phosphatidyl choline. The surfactants are not limited to theones mentioned above.

[0130] The additive which may be incorporated into the ink compositionof the present invention includes acid-generating agents, polymerizationinitiators and crosslinking agents which can be activated by heat orelectromagnetic wave.

[0131] Other additives which may be incorporated into the inkcomposition in the present invention include pH-adjusting agents forstabilization of the ink and stability of the ink in the ink pipe;penetrating agents for accelerating the ink penetration into therecording medium and facilitating apparent drying; fungicides forpreventing growth of fungi; chelating agent for blocking metal ions toprevent deposition of a metal in the nozzle and deposition of aninsoluble matter in the ink; antifoaming agent for preventing foamformation in circulation, transfer, or production of the recordingliquid; antioxidants; viscosity-adjusting agents; electric conductingagents, UV-absorbing agents; and coloring agents such as water-solubledyes, dispersion dyes and oil-soluble dyes.

[0132] The ink composition of the present invention is preferably usedas an ink for ink-jet recording. A method for preparing the ink forink-jet recording is explained below.

[0133] (Method for Preparation of Ink for Ink-Jet)

[0134] In a example of preparing the ink composition for ink-jetrecording of the present invention, a pigment, a block polymer of thepresent invention, and an additive are added to deionized water, and aredispersed by a dispersing machine; coarse particles are eliminatedtherefrom by centrifugation or a like method; and thereto water or asolvent and an additive are added and the mixture is stirred forcomplete mixing, and is filtered.

[0135] The dispersing machine includes ultrasonic homogenizers,laboratory homogenizers, colloid mills, jet mills, and ball mills. Themachines may be used singly or in combination.

[0136] A composition employing a self-dispersible pigment can beprepared in the same manner as above.

[0137] Next, the image-forming method of the present invention isexplained below.

[0138] (Image-Forming Method)

[0139] The ink composition of the present invention is useful for imageformation by various image-forming methods such as printing, ink-jetrecording, and electrophotography, being especially suitable for ink-jetrecording.

[0140] The ink-jet recording may be conducted by any known ink-jetmethod including piezo ink-jet methods using a piezo element, thermalink-jet method utilizing bubbling by thermal energy. The ink-jet methodmay be conducted by a continuous system or by an on-demand system.Further, the ink composition of the present invention may be used fortransfer recording method in which an image is printed on anintermediate transfer medium with the ink and the formed image istransferred onto a final recording medium such as a paper sheet.

[0141] The stimulation-responsive ink-jet composition of the presentinvention can be used as an ink-jet recording ink in the modes bystimulation (a) to (d) as shown below.

[0142] (a) Ink Responsive to Temperature Stimulation:

[0143] A temperature difference between the ink in the ink tank and theink deposited by ejection on a recording medium gives a temperaturestimulation to cause phase change of the ink composition for ink-jetrecording, resulting in quick viscosity increase of the composition oraggregation of the insoluble component.

[0144] (b) Ink Responsive to Electromagnetic Stimulation:

[0145] Exposure of the ink composition having been stored in a dark inktank to visible light by ejection, or irradiation of electromagneticwave from an electromagnetic wave irradiation unit gives anelectromagnetic stimulation to cause polymerization of the polymerizablefunctional group contained in the ink composition for ink-jet recordingof the present invention to cause viscosity increase or aggregation ofan insoluble component.

[0146] (c) Ink Responsive to pH Change Stimulation:

[0147] Deposition onto the recording medium causes pH change of the inkcomposition by the influence of the recording medium, the pH changeresulting in viscosity increase or aggregation of an insolublecomponent.

[0148] (d) Ink Responsive to Concentration Change Stimulation:

[0149] Evaporation of water or an aqueous solvent from the ejected inkcomposition or absorption thereof by the recording medium causesconcentration change in the ink composition to give phase change,resulting in viscosity increase or aggregation of an insolublecomponent.

[0150] The change of the properties of the ink composition enablesretardation of color running or feathering to obtain high inkfixability. Incidentally, the property change is not limited to theviscosity increase or the aggregation of the insoluble component.

[0151] The stimulation can be given in various methods. In a preferredmethod, a stimulating substance for the intended stimulation is mixedwith or brought into contact with the stimulation-responsive inkcomposition. For example, to the pH-responsive ink mentioned in theabove item (c), a corresponding pH-stimulating substance is mixed byink-jet method. By the ink-jet method, the stimulating substance may bedotted by an ink-jet head over the entire area of image formation asdisclosed in Japanese Patent Application Laid-Open No. 64-63185, or thequality of the formed image can be improved by controlling the amount ofthe stimulating substance as disclosed in Japanese Patent Laid-Open No.8-216392.

[0152] Otherwise, one of the compositions containing the dye or pigmentcan be utilized as the stimulating substance. For example, in a colorink-jet recording, a stimulating ink is used as one of the inks of cyan,magenta, yellow, and black (CMYK), and a stimulation-responsive ink isused as another one of CMYK inks to retard color running. Variouscombinations of the stimulation-responsive ink and the stimulating inkare possible from among the inks of CMYK, but the selection of thecombination is not limited in the present invention. Furthermore, thekind of the stimulating substance and the kind of thestimulation-responsive ink composition may be selected from all of theaforementioned stimulation response patterns, and is not limitedspecially.

[0153] The image-forming apparatus of the present invention is explainedbelow.

[0154] (Image Recording Apparatus)

[0155] The ink composition of the present invention is useful inimage-forming apparatuses utilizing an image-forming method such asprinting methods, ink-jet method, and electrophotography, usefulparticularly in ink-jet recording apparatus.

[0156] The ink-jet recording apparatus employing the ink for ink-jetrecording includes apparatuses of piezo ink-jet systems employing apiezo element, and apparatuses of thermal ink-jet systems utilizing athermal energy for ink ejection by bubbling.

[0157]FIG. 1 shows schematically the system 20 of the image-formingapparatus of the present invention. The numeral 50 indicates a centralprocessing unit (CPU). The program for controlling CPU 50 may be storedin program memory 66, or may be stored in storage means like EEPROM (notshown in the drawing) as a so-called firmwear. The ink-jet recordingapparatus receives recording data from a recording data-forming means (acomputer or the like, not shown in the drawing) and stores the data byprogram memory 66. The recorded data may be image information orcharacter information itself to be recorded, or may be compressedinformation, or coded information. The compressed or coded informationto be treated is expanded or depressed by CPU 50 to obtain the image orcharacter information to be recorded. X-encoder 62 (e.g., for Xdirection or for the main scanning direction) and Y-encoder 64 (e.g.,for Y direction or the auxiliary scanning direction) are provided tocommunicate the position of the head relative to the recording medium toCPU 50.

[0158] CPU 50 transmits signals for image recording to X-directiondriving circuit 52, Y-direction driving circuit 54, and head-drivingcircuit 60 according to the information from program memory 66, Xencoder 62, and Y encoder 64. X-direction driving circuit 52 drivesX-direction driving motor 56, and Y-direction driving circuit 54 drivesY-direction driving motor 58 to move head 70 relatively to the recordingmedium to the recording position. At the moment when head 70 has come tothe recording position, head-driving circuit 60 transmits signals forejecting the ink composition (Y, M, C, or K) or a stimulating substanceto head 70 to conduct recording. The head 70 may be the one for ejectinga single color ink composition, or the one for ejecting plural inkcompositions, or may have additionally a function of ejecting astimulating substance.

[0159] The ink composition of the present invention may be used in adirect recording system which ejects the ink directly onto a recordingmedium, or in a transfer recording system in which an ink image isformed on an intermediate transfer member having a latent image and theimage is transferred onto a final recording medium such as a papersheet. Otherwise, the ink composition of the present invention may beused in an apparatus of direct recording system utilizing intermediatetransfer member.

[0160] The recording medium of the present invention is described below.

[0161] (Recording Medium)

[0162] The stimulation mechanism may be provided on a recording mediumto stimulate the stimulation-responsive ink composition of the presentinvention.

[0163] In the image formation, as described above, the stimulatingsubstance may be mixed with or brought into contact with thestimulation-responsive ink composition. Otherwise a stimulatingmechanism may be provided on the recording medium preliminarily. Forexample, (1) an acid-responsive ink composition is used as thepH-responsive ink composition, and recording is conducted on an acidicpaper sheet; (2) a pH-responsive ink composition is used as thestimulation-responsive ink composition, and recording is conducted on arecording medium which releases a pH-changing substance by applicationof heat, electromagnetic wave, or pressure; and (3) astimulation-responsive ink containing a crosslinkable or polymerizablefunctional group is used as the ink composition, and recording isconducted on a recording medium which releases a pH-changing substanceby application of heat, electromagnetic wave, or pressure. The recordingmedium in the present invention may be of any known kind, includingplain paper sheets, thermosensitive paper sheets, and acidic papersheets.

[0164] In the recording by the direct recording system, the aboverecording medium is used as the final recording medium. In the recordingby the indirect recording system, the above recording medium may beemployed as an intermediate transfer member, or as the final recordingmedium.

[0165] As described above and the following examples, the presentinvention provides a composition containing a particulate substancedispersed well in a solvent, and a block polymer having an ionicfunctional group.

[0166] The present invention provides also a functional compositionwhich is an aqueous uniform dispersion.

[0167] The present invention provides further an ink compositioncontaining a pigment as the particulate substance, water as the solvent,in which the pigment is dispersed with high dispersibility.

[0168] The present invention provide further a pigment-dispersion inkcomposition for ink-jet recording, which contains a particulate pigmentmaterial dispersed with high dispersion stability in the solvent, andwhich forms an image with high fixability and high smearing resistance.

[0169] The present invention provides still further an image-formingmethod employing the above pigment-dispersion ink composition forink-jet recording, and an image-forming apparatus for the image-formingmethod.

EXAMPLES

[0170] The present invention is explained below in more detail withoutlimiting the invention thereto. In the examples below, are explained amethod of synthesis of a block polymer having an ionic functional groupof the present invention, and a pigment dispersion-ink composition as anaqueous dispersion. Incidentally, only few methods are shown in Examplesof the polymer synthesis and pigment-dispersion ink, but the presentinvention is not limited thereto.

Example 1

[0171] (Synthesis of Block Polymer)

[0172] Synthesis of ABX Type Block Polymer Constituted of 2-EthoxyethylVinyl Ether (EOVE), 2-Methoxyethyl Vinyl Ether (MOVE), and HO(CH₂)₅COOH:

[0173] Poly[EOVE(2-ethoxyethyl vinyl ether)-b-MOVE(methoxyethyl vinylether)]-O(CH₂)₅COOH was synthesized through the following steps (here, bis a symbol denoting a block polymer).

[0174] A glass vessel having a three-way cock is purged with a nitrogen,and was heated 250° C. under a nitrogen atmosphere to remove adsorbedwater. After returning the system to room temperature, thereto wereadded 12 mmol of EOVE, 16 mmol of ethyl acetate, 0.1 mmol of1-isobutoxyethyl acetate, and 11 mL of toluene. The reaction system wascooled. When the temperature of the system reached 0° C., 0.2 mmol ofethylaluminum sesquichloride (equimolar mixture of diethyaluminumchloride and ethylaluminum dichloride) to initiate polymerization. Themolecular weight was monitored intermittently by molecular sieve columnchromatography (GPC). Thereby the completion of polymerization of Acomponent (EOVE) was confirmed.

[0175] Thereto, 12 mmol of the B component (MOVE) was added, and wasallowed to polymerize. After the completion of polymerization of the Bcomponent was confirmed by GPC monitoring, 30 mmol of HO(CH₂)₅COOEt wasadded thereto to stop the polymerization reaction. The reaction mixturesolution was diluted with dichloromethane, and the diluted mixture waswashed three times with 0.6M hydrochloric acid, and three times withdistilled water. The organic phase after washing was evaporated todryness to obtain a block polymer of poly[EOVE-b-MOVE]-O(CH₂)₅COOEt.

[0176] The synthesized compound was identified by GPC and NMR. Inparticular, the moiety bonding to the terminal was identified by a DOSYmethod of NMR, thereby the presence of a terminal portion beingconfirmed. The obtained polymer had Mn of 2.1×10⁴, and Mw/Mn of 1.4 (Mndenotes a number-average molecular weight, and Mw denotes aweight-average molecular weight).

[0177] The terminal ester moiety of the obtainedpoly[EOVE-b-MOVE]-O(CH₂)₅COOEt was hydrolyzed. The hydrolysis productwas identified by NMR, and was found to bepoly[EOVE-b-MOVE]-O(CH₂)₅COOH, an intended ABX type block polymer.

Example 2

[0178] A polymer compound, an isobutyl vinyl ether polymer having a—O—(CH₂)₅COOH group at the terminal, was synthesized in the same manneras in Example 1, using 3 mmol of isobutyl vinyl ether as a monomer. Thepolymer compound had a number-average molecular weight of 6,000, and amolecular weight distribution Mw/Mn of 1.11.

Example 3

[0179] A portion of 26 parts by weight of the block polymer having acarboxylic acid terminal obtained in Example 1 was stirred with 200parts by weight of an aqueous sodium hydroxide solution of pH 11 forthree days to obtain a sodium salt of polymer-carboxylic acid.

[0180] A portion of 25 weight parts of this solution was mixed with 10weight parts of diethylene glycol, 5 weight parts of 2-pyrrolidone, 3weight parts of carbon black (trade name: MOGUL-L, Cabot Co.), and 57parts by weight of deionized water, and stirred by a homogenizer. Fromthe resulting mixture, coarse particles were eliminated by filtration toobtain a pigment dispersion ink composition.

[0181] On contact of this ink composition with a 5 mass %polymethacrylic acid solution adjusted to pH 2, black gel was formedinstantaneously, showing the stimulation-responsiveness of the inkcomposition.

[0182] The ink composition, on cooling to 10° C., became viscousapparently. This means presumably that the A block segment of the usedblock polymer, namely the EOVE block, changes to be hydrophilic toresult in complete dissolution in a molecular state of the blockpolymer.

Example 4

[0183] The polymethacrylic acid solution of pH 2 described in Example 3was sprayed preliminarily on a plain paper sheet. On this paper sheet,recording was conducted by ejecting the ink prepared in Example 3 from aprinting head of an ink-jet printer (trade name: BJF800, Canon Inc.).

[0184] One minute later, for evaluation of fixation of the ink, anotheruntreated plain paper sheet was pressed against the printed paper sheetat a load of 4.9×10⁴ N/m². The fixation strength was evaluated byoccurrence or nonoccurrence of transfer of the ink onto the untreatedplain paper sheet. As the result, the transfer of the ink was notobserved. This test was repeated five times to obtain invariably thesame result.

Example 5

[0185] Recording was conducted in the same manner as in Example 4 exceptthat an untreated plain paper was used as the recording medium and thearea of the paper sheet to be dotted with the ejected ink was cooled to10° C. in the ink-jet printer. The fixation strength test was conductedfive times. In the two of the five repetitions of the test, black colorwas observed to be slightly transferred.

Comparative Example 1

[0186] An ink composition was prepared by mixing 5 mass parts of aself-dispersible pigment (trade name CAB-0-JET300, Cabot Co.), 0.5 massparts of a surfactant (Nonion E-230, Nihon Yushi K.K.), 5 mass parts ofethylene glycol, and 89.5 mass parts of deionized water. The recordingtest and fixation test was conducted in the same manner as in Example 4.As the result, the ink transfer to the untreated plain paper wasobserved.

What is claimed is:
 1. A composition containing a polymer having anionic functional group, comprising a particulate substance, a solvent,and a polymer having at least one selected from the group consisting ofan ionic functional group, an acid residue and a base residue at theterminal.
 2. The composition according to claim 1, wherein the polymeris a block polymer having at least one selected from the groupconsisting of an ionic functional group, an acid residue and a baseresidue at the terminal.
 3. The composition according to claim 2,wherein the polymer having at least one selected from the groupconsisting of an ionic functional group, an acid residue and a baseresidue at the terminal is a block polymer containing segments of A, Band X, where A and B are respectively a block segment having a vinylether structure as the repeating unit, and X is a terminal segmenthaving at least one selected from the group consisting of an ionicfunctional group, an acid residue and an base residue.
 4. Thecomposition according to claim 3, wherein the block segment A iscomprised of the repeating unit represented by the following GeneralFormula (1):

(in the formula, R₁ is selected from the group consisting of linear andbranched alkyl groups of 1-18 carbons, -Ph, -Pyr, -Ph-Ph, -Ph-Pyr,—(CH(R₅)—CH(R₆)—O)_(p)—R₇, and —(CH₂)_(m)—(O)_(n)—R₇; the hydrogen atomin the aromatic ring may be substituted by a linear or branched alkylgroup of 1-4 carbons; and the carbon atom in the aromatic ring may besubstituted respectively by a nitrogen atom; p is an integer of 1 to 18,m is an integer of 1 to 36, n is 0 or 1; R₅ and R₆ are independently —Hor —CH₃; R₇ is selected from the group consisting of Hydrogen, linearand branched alkyl groups comprising 1 to 18 carbons, -Ph, -Pyr, -Ph-Ph,-Ph-Pyr, —CHO, —CH₂CHO, —CO—CH═CH₂, —CO—C(CH₃)═CH₂, —CH₂COOR₈, and whenR₇ is other than a hydrogen atom, the hydrogen atom bonding to a carbonatom in R₇ may be substituted by a substituent selected from the groupconsisting of a linear or branched alkyl group of 1-4 carbons, —F, —Cland —Br, and the carbon atom in the aromatic ring may be substitutedrespectively by a nitrogen atom; R₈ is H or an alkyl of 1-5 carbons; Phrepresents phenyl, and Pyr represents pyridyl).
 5. The compositionaccording to claim 3, wherein the block segment B is comprised of therepeating unit represented by the following General Formula (2):

(in the formula, R2 is selected from the group consisting of -Pyr,—(CH(R₅)—CH(R₆)—O)_(p)—R₇ and —(CH₂)_(m)—(O)_(n)—R₇; p is an integer of1 to 18, m is an integer of 1 to 36, n is 0 or 1; R₅ and R₆ areindependently —H or —CH₃; R₇ is selected from the group consisting ofHydrogen, linear and branched alkyl groups comprising 1 to 18 carbons,-Ph, -Pyr, -Ph-Ph, -Ph-Pyr, —CHO, —CH₂CHO, —CO—CH═CH₂, —CO—C(CH₃)═CH₂,—CH₂COOR₈, and when R₇ is other than a hydrogen atom, the hydrogen atombonding to a carbon atom in R₇ may be substituted by a substituentselected from the group consisting of a linear or branched alkyl groupof 1-4 carbons, —F, —Cl and —Br, and the carbon atom in the aromaticring may be substituted respectively by a nitrogen atom.
 6. Thecomposition according to claim 3, wherein the ionic functional group orthe acid residue or the base residue of the terminal segment X isselected from the group consisting of carboxylic acid, sulfonic acid,phosphoric acid, metal salts thereof, amines, and acid salts of amines.7. The composition according to claim 3, wherein the terminal segment Xis represented by the following General Formula (3):

(in the formula, L is a coupling group for coupling with the terminal ofa block polymer selected from the group consisting of a single bond,—O—, —COO—, —OCO—, —CONH— and —NHCO—; M is a substituted orunsubstituted linear or branched alkylene group of 1-30 carbons; R₉ andR₁₀ are independently selected from the group consisting of a hydrogenatom, an alkyl group, COOR₁₁ and NR₁₁R₁₂; R₁₁ and R₁₂ representindependently a substituent selected from the group consisting of ahydrogen atom, an alkyl group, and a counter ion group of the carboxyanion; Z represents a substituent selected from the group consisting of—COOH, a carboxylic ester group, —COO⁻, —SO₃H, a sulfonic ester group,—SO₃ ⁻, —OPO₃H₂, phosphoric ester group, —OPO₃H⁻, —OPO₃ ²⁻, an aminogroup and an acid salt of an amino group).
 8. The composition accordingto claim 1, wherein the particulate substance is a pigment.
 9. Thecomposition according to claim 1, wherein the solvent is water.
 10. Thecomposition according to claim 2, wherein the block polymer isresponsive to stimulation to change the properties thereof.
 11. Thecomposition according to claim 10, wherein the stimulation is any oneselected from the group consisting of temperature change, exposure toelectromagnetic wave, pH change and concentration change.
 12. An inkcomposition, comprising the composition set forth in claim
 1. 13. Theink composition according to claim 12, the ink composition is an ink-jetink composition.
 14. An image-forming method, employing the inkcomposition set forth in claim
 12. 15. An image-forming method forrecording an image by ejecting an ink from an ink ejection unit onto arecording medium, wherein the ink is the ink composition set forth inclaim
 12. 16. The image-forming method according to claim 14, whereinimage is formed by fixation of the ink composition on a recording mediumby contact of the ink composition with a stimulating substance whichgives stimulation to the ink composition.
 17. The image-forming methodaccording to claim 16, wherein the stimulating substance is providedpreliminarily on the recording medium.
 18. The image-forming methodaccording to claim 15, wherein the ejection of the ink from the inkejection unit is conducted by action of thermal energy to the ink. 19.An image-forming apparatus, employing the image-forming method set forthin claim
 15. 20. A recording medium for the image-forming method inwhich the ink composition set forth in claim 12 is ejected from anink-ejection unit onto a recording medium, wherein a stimulatingsubstance for stimulating the ink composition is preliminarily providedon the recording medium.
 21. A block polymer containing segments of A,B, and Y, where A and B are block segments having a vinyl etherstructure as the repeating unit, and Y is a terminal segment representedby the following General Formula (4): —L′—M′—Z′  (4) (in the formula, L′is a coupling group for coupling with the terminal of a block polymerselected from the group consisting of a single bond, —O—, —COO—, —OCO—,—CONH— and —NHCO—; M′ is a substituted or unsubstituted linear orbranched alkylene group of 2-30 carbons; and Z′ represents a substituentselected from the group consisting of —COOH, a carboxylic ester group,—COO⁻, —SO₃H, a sulfonic ester group, —SO₃ ⁻, —OPO₃H₂, a phosphoricester group, —OPO₃H⁻, —OPO₃ ²⁻, an amino group, and an acid salt of anamino group).